Palladium catalyzed crosscoupling reactions

Mixed trialkylstannyl and silyl derivatives have also been used in coupling reactions, with subsequent replacement of the silyl substituent by bromine, leading to species that are capable of undergoing further coupling reactions. This process was amply demonstrated by the recent synthesis of micrococcinic acid 203, which involved four palladium-catalyzed crosscoupling reactions on stannylated substrates, two palladium-catalyzed trimethylstannane replacements of bromine, two trimethylsilyl displacements by bromine, and a total of four bromine-lithium exchange reactions, on three different thiazole derivatives and one pyridine derivative (91-TL4263). 

Synthesis of a-fluoro-ot, -unsaturated ketones via palladium-catalyzed crosscoupling reaction of 1-fluorovinyl halides (79) with organostannanes (80)... 

Iightowler, S. and Hird, M. (2005) Monodisperse aromatic oligomers of defined structure and large size through selective and sequential Suzuki palladium-catalyzed crosscoupling reactions. Chemistry of Materials A Publication of the American Chemical Society, 27, 5538 -9. 

In order to facilitate the desired palladium-catalyzed creation of the welwistatin C4-C11 bond, compound 70 was regioselectively transformed into /3-kclocslcr 65 by treatment with LDA in the presence of HMPA, followed by addition of Mander s reagent. The crucial palladium-catalyzed crosscoupling reaction took place in the presence of palladium acetate, th-tert-butylphosphine and potassium ferf-butoxide, and afforded compound 64, which contains the complete welwistatin skeleton. The installation of a nitro-... 

Traceless solid-phase synthesis of 2,6,9-trisubstituted purines from resin-bound 6-thiopurines <02T7911>, and microwave assisted solid-phase synthesis of 2,6,9-trisubstituted purines <02TL6169> have been described. A resin-capture and release strategy toward combinatorial libraries of 2,6,9-trisubstituted purines has been reported <02JCO183>. Alkylated purines chlorinated at the 6,8- or 2,6,8-positions can be captured onto a solid support and further elaborated by aromatic substitution or via palladium catalyzed crosscoupling reactions <02JA1594>. 

Previously Davidson and Triggs have reported that arylboronic acids react with sodium palladate to give the dimeric biaryls. The synthetic utility of this dimerization reaction is, however, limited owing to stoichiometric requirement of the palladium compound. On the other hand, the palladium-catalyzed crosscoupling reaction between arylboronic acids and haloarenes in the presence of bases provides a clean synthesis of biaryls (Eq. 106) In this case, sodium carbonate has been proven to be most effective base. 

Old, D.W. Wolfe, J.P. Buchwald, S.L. Highly active catalyst for palladium-catalyzed crosscoupling reactions room-temperature Suzuki couplings and amination of unactivated aryl chlorides. J. Am. Chem. Soc. 1998, 120, 9722. 

Over the past century, several methods have been developed for the synthesis of biaryl compounds [7]. Among these are the Ullmann-type coupling [8,9], the Scholl reaction [10], the Gomberg-Bachmann reaction [11], and recently transition-metal-catalyzed cross-coupling reactions [12], In particular, palladium-catalyzed crosscoupling reactions have been successfully applied to the synthesis of biaryls due to their generally high yields and excellent selectivities. 

Recently, de Lera et al. have carried out regioselective palladium-catalyzed crosscoupling reactions, Suzuki coupling and Stille coupling, in the synthesis of novel 2,3-disubstituted thiophene derivatives. They reported that regioselective coupling at C2 could be accomplished efficiently by Suzuki coupling under similar conditions (Equations 33 and 34) [34]. 

Alkenylpentafluorosilicates derived from terminal alkynes react readily with allylic substrates in a palladium-catalyzed crosscoupling reaction to yield ( -1,4-dienes (eq 21). Treatment of 1-alkenylstannanes with t-BuOOH in the presence of 10% of palladium acetate gives 1,3-dienes (eq 22), whereas coupling between 1- and 2-alkenylstannanes provides 1,4-dienes in good yields (eq 23). ... 

DK Morita, SA David, W Tumas, DR Pesiri, WH Glaze. Palladium-catalyzed crosscoupling reactions in supercritical carbon dioxide. Chem Commun 1397-1398, 1998. 

The history of the discoveries and developments of the palladium-catalyzed crosscoupling reactions has been documented in many reviews, book chapters, and monographs. Palladium-catalyzed processes can be traced back to Nickel-catalyzed cross-coupling reactions of organomagnesium derivatives reported in 1972 by Tamao, Sumitani, and Kumada as well as by Corriu and Masse. Some groups led by Murahashi et Fauvarque, and Sekiya and Ishikawa independently... 

Scheme 5-104. Hydroalumination and subsequent palladium-catalyzed crosscoupling reaction. ...

The literature on the potential applications of Pd-catalyzed crosscoupling reactions for the syntheses of specialty chemicals, pharmaceuticals, and fine chemicals is vast. We begin with two of the earliest examples of industrial applications of Heck-Mizoroki reactions. As shown by (7.4.2.1) and (7.4.2.2), for making the herbicide Prosulfuron and the analgesic R-naproxen, palladium-catalyzed crosscoupling reactions are used in the first steps. 

Structures of three other valuable products 7.61-7.63 are shown later. Total syntheses of all the three include palladium-catalyzed crosscoupling reaction as one of the steps. The synthesis of 7.61, which is used in electronic industries as an adhesive, involves the Heck-Mizoroki reaction, while that of 7.62 and 7.63 includes Negishi and Suzuki-Miyaura reactions, respectively. 

Braga AAC, Ujaque G, Maseras F (2008) Mechanism of palladium-catalyzed crosscoupling reactions. In Morokuma K, Musaev DG (eds) Computational modeling for homogeneous and enzymatic catalysis. Wiley-VCH, Weinheim... 

GoojSen LJ, Koley D, Hermann HL, Thiel W (2005) The palladium-catalyzed crosscoupling reaction of carboxylic anhydrides with arylbotonic acids a DFT study. J Am Chem Soc 127 11102-11114... 

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